This invention relates to an apparatus for and method of remotely opening a door.
If there is a suspicion or knowledge that there is an unexploded device behind a door or the door is booby trapped it is desirable to open the door remotely, that is with the person opening the door positioned some distance away from the door, in case the act of opening the door triggers the unexploded device.
Remote opening of a door is relatively straightforward if the door opens towards the operator's side of the door. For example, a rope can be attached to the door handle which when pulled activates the door handle to unlatch the door which can then be opened by further pulling on the rope. Such a technique is not possible, however, if the door opens away from the operator's side of the door.
A known approach to the latter situation is disclosed in CA-A-2,543,750 which discloses a remote door opening apparatus that includes a support bar having a lever arm which can be urged outwards by a gas cylinder. A pulling line extends from a remote operator position to a guide on the support bar up to a door handle and is looped through a release pin. When the pulling line is pulled the line acts to unlatch the door handle. Once unlatched continued pulling of the pulling lines pulls out the release pin so releasing the lever arm which is moved to a position at right angles to the support bar. Alternatively, the pin could be released before door handle is unlatched.
This known device applies a predetermined force to the door and operates to immediately extend the lever arm to the most extended position. There are, however, circumstances when it is desirable to gradually open a door or to apply a greater force than is expected to be needed, e.g. if the door is stuck in the closed position.